Built in 1638 by the Emperor Shah Jahan, the "forbidden city" of Old Delhi, encircled by red sandstone walls, housed the emperor's government and palaces. The fort is accessed by the Lahore monumental gate. The two most emblematic buildings are the two halls of audience: the Diwan-i Am, where the emperor, seated on a marble throne adorned with pietra dura, received his official guests; and the Diwan-i Khas, used for private audiences, which was stripped of its legendary "peacock throne" (decorated with precious stones) by the king of Persia in 1739.